Hello Valentin,

Thank you for reporting this error. The built-in speech recognizer in our RadSpeechToTextButton control is based on the Web Speech API and is utilized via WebView2. Microsoft states that its Web Speech API implementation uses Azure Cognitive Services. The error points to the underlying speech-recognition communication, rather than the button’s UI functionality. Nevertheless, we will investigate further to determine the cause of this error, as the error message itself provides little information.

Regards,
Dinko | Tech Support Engineer
Progress Telerik